People who live in glass houses shouldn’t throw stones.

This is a proverb. It is also a metaphor.  The Oxford Dictionary of Phrase, Saying and Quotation has it filed under gossip.  I’ll let you draw your own conclusions.

It’s all over bar the shouting.
Bar here means except for.  People may be upset and go on talking about it.

He’s on his hobby-horse,
metaphorically) talking about the subject which is dearest to him.  A notable use of this expression is in Laurence Sterne’s book, Tristram Shandy.  A hobby-horse is a toy horse to ride on.

William Wallace Denslow’s illustrations for a variant of Ride a cock horse, from a 1901 edition of Mother Goose. (Wikipedia)

If I’ve told you once, I’ve told you a hundred times
is a frustrated mother’s complaint to her lazy or disobedient children.

Make no mistake about it…
I want you to take my word for it.

I mean to say…
…introduces something the speaker thinks is important.

We’re not on the same wavelength.

An expression which came in with the invention of radio and television, meaning that there is a difference of opinion or misunderstanding.

We’ve got our wires/lines crossed.

Another, this time  from telephones.  Crossed-lines are far less common nowadays, but sometimes a phone conversation could end up being 3 or 4 way by mistake!

We seem to be at cross-purposes.
An older expression for the same thing,

He got the wrong end of the stick.
Another one.

It’s music to my ears.
Someone is hearing pleasant things (about themselves).

It’s cut and dried.
Like hay?  Nothing can be changed.

Look me in the face and tell me…
…I have doubts about the truth of your story.

You’ve cottoned on to that.
Cottoned on means understood or got the hang of.  Both are slang expressions and getting the hang of tends to be more practical.

I can read you like a book.
This is about facial expression as much as what is said.  It is a comparison, but not a simile or metaphor.

It isn’t a matter of life and death.
Reassurance to someone who is upset.

It isn’t the end of the world.
More of the same.

In the Book of Common Prayer the Gloria is used after each psalm.  It finishes “world without end. Amen”.  Is this a reference to the angel’s promise in Luke Chapter 1 verse 33  “…his kingdom will never end” or another way of saying “for ever and ever”?